As shown in FIG. 22 to FIG. 29, to a conventional rainwater discharge chamber 100, a rainwater discharge chamber main body 102, a confluent sewage line inflow pipe (referred to as a “confluent pipe” when necessary) 104, a dirty water pipe 106, and a rainwater pipe 108 are connected. Here, sewage (dirty water (domestic waste water)+rainwater) flows into the confluent pipe 104, the dirty water pipe 106 leads to a sewage treatment apparatus, and the rainwater pipe 108 leads to a public water area such as a river or the like.
Inside the rainwater discharge chamber main body 102, a first flowing water channel 110 is formed through which the sewage flowing in from the confluent pipe 104. The first flowing water channel 110 is provided to connect the confluent pipe 104 and the dirty water pipe 106, and a weir 112 having a predetermined height is formed on one side thereof in the width direction. Therefore, the sewage flowing in from the confluent pipe 104 will flow through the first flowing water channel 110 surrounded on both sides by an inner wall of the rainwater discharge chamber main body 102 and the weir 112 to the dirty water pipe 106 side. Further, when the water quantity of the sewage flowing in from the confluent pipe 104 is equal to or less than a predetermined quantity, the sewage never flows over the weir 112 but all the water quantity of the sewage flowing in from the confluent pipe 104 flows into the dirty water pipe 106 through the first flowing water channel 110 and is conveyed to the sewage treatment apparatus.
Further, inside the rainwater discharge chamber main body 102 and below the first flowing water channel 110, a second flowing water channel 114 is formed through which the sewage flowing over the weir 112 of the first flowing water channel 110 flows. The second flowing water channel 114 is connected to a rainwater pipe 108, so that the sewage flowing over the weir 112 of the first flowing water channel 110 flows through the second flowing water channel 114 and then flows into the rainwater pipe 108 to be conveyed to a public water area such as a river or the like.
As described above, according to the conventional rainwater discharge chamber 100, when the water quantity of the sewage flowing from the confluent pipe 104 into the rainwater discharge chamber main body 102 is equal to or less than a predetermined quantity as shown in FIG. 22 to FIG. 25, the sewage flowing into the rainwater discharge chamber main body 102 never flows over the weir 112 but flows through the first flowing water channel 110 as it is to enter the dirty water pipe 106. Then, the sewage in the dirty water pipe 106 is conveyed to the sewage treatment apparatus.
On the other hand, when the water quantity of the sewage flowing from the confluent pipe 104 into the rainwater discharge chamber main body 102 is greater than the predetermined quantity as shown in FIG. 26 to FIG. 29, the sewage flowing into the rainwater discharge chamber main body 102 flows through the first flowing water channel 110 and a part of it flows over the weir 112 to flow through the second flowing water channel 114. Therefore, the sewage flowing through the first flowing water channel 110 to enter the dirty water pipe 106 flows into the sewage treatment apparatus, and the sewage flowing through the second flowing water channel 114 to enter the rainwater pipe 108 flows into the public water area such as a river or the like.
Patent Document 1: Japanese Patent Application Laid-open No. 2004-27701